(1) Field of the Invention
The present invention is directed generally toward a system and method of use for analyzing reflected acoustic fields directed towards a resolution target underwater or in the atmosphere and more specifically toward a system and method of use for fully decomposing a reflected acoustic field into acoustic intensity vector components.
(2) Description of the Prior Art
Sonar systems are well known in the art for tracking and identifying submerged objects or objects in the atmosphere, for mine hunting, for precision underwater mapping and multistatic applications where there is more than one source and/or a receiver.
One sonar system example is a ship that can tow an array of sound-receiving hydrophones arranged in a passive towed array. The passive towed array, in conjunction with sound receiving and signal processing electronics, can detect sound in the water that may indicate the presence of an underwater target. In other arrangements, the ship can tow both the passive towed array and a towed acoustic projector, which together form a bi-static active sonar system. With this arrangement, the towed acoustic projector emits sound pulses.
Each sound pulse travels through the water, striking an object or target in the water, which in turn produces echoes. The echoes are received by the towed array of receiving hydrophones. Therefore, an echo indicates the presence of an underwater object and the direction from which the echo came; subsequently, indicating the direction of the underwater object.
In conventional bi-static active sonar systems, the towed acoustic projector is often deployed and towed separately from the towed array sound receiving hydrophones. A conventional towed acoustic projector typically includes a sound source mounted within a large rigid tow body. The conventional towed acoustic projector is large and heavy.
The towed acoustic projector is typically used to detect objects in deep water and at long ranges. Therefore, the acoustic projector is capable of generating sound having a high pressure level in order to enable the system to receive echoes from and to detect objects in the deep water at long ranges.
The towed array of receiving hydrophones are often deployed and recovered through a hull penetrator below the ship water line. In contrast, in part due to size and weight, the towed acoustic projector is deployed and recovered over the gunwale of the ship with winch and boom equipment.
U.S. Pat. No. 5,438,552 discloses a sonar system for identifying objects including a technique for providing a two-dimensional array of pixels, each one of the pixels representing the intensity of a signal at a predetermined range position and a predetermined cross-range position from a reference position and quantizing the intensity of each one of the pixels into one of a plurality of levels. The technique further includes comparing a distribution of the levels of pixels over a range scan at a cross-range position with the distribution of levels of pixels over a range scan at a different cross-range position to identify the existence of a foreign object such as a mine.